Supermarket fridges now hold almost as many plant milks as dairy ones: soy, oat, almond, coconut, rice, pea. They’re often sold as the healthier choice. Some of them are, for some people. Many of them, nutritionally, are closer to flavoured water with added calcium than to a glass of milk. So when you compare plant milk vs cow milk, what are you actually gaining or losing?
This article is part of our evidence-based guide to healthy drinks. Below we compare protein, calcium and other nutrients, look at what official dietary guidance says, and cover who should be careful about switching, especially young children. It is general information, not medical advice.
Plant Milk vs Cow Milk: The Quick Answer
- Fortified, unsweetened soy milk is the only common plant milk that comes close to cow’s milk across the board.
- Almond, oat, rice and coconut drinks are usually much lower in protein. They’re fine as part of an adult diet if you get protein elsewhere, but they aren’t a like-for-like replacement.
- Calcium in plant milks depends almost entirely on fortification, so check the label for it.
- Young children have stricter rules. Plant milks generally aren’t recommended as a main drink for under-5s unless there’s a medical reason, and rice drinks shouldn’t be given to under-5s at all.
Protein: The Biggest Difference
A cup (about 240 ml) of cow’s milk contains a little over 8 g of protein. A Mayo Clinic comparison puts soy milk at about 7 g per cup and traditional almond milk at about 1 g.
A 2018 review by Sai Kranthi Vanga and Vijaya Raghavan at McGill University, published in the Journal of Food Science and Technology, compared the four most popular plant drinks (almond, soy, rice and coconut) using nutrition labels from several commercial brands. They concluded that soy was the best alternative to cow’s milk. Rice drinks were mostly carbohydrate, and coconut drinks got most of their calories from saturated fat with almost no protein. Almond drinks had a pleasant taste but were low in calories and nutrients.
A larger 2023 analysis showed how wide the gap still is. Researchers at the University of Minnesota’s Nutrition Coordinating Center examined 233 plant-based milk products from 23 manufacturers sold in the US, and presented the results at NUTRITION 2023, the American Society for Nutrition’s annual meeting. The median protein content was just 2 g per 240 ml, compared with 8 g in cow’s milk. Soy- and pea-based products were the most likely to have higher protein. Only 28 of the 233 products (about 12%) matched or beat dairy milk on protein, calcium and vitamin D together. The analysis was based on labels and ingredient lists, not lab tests.
Does this matter? For most adults eating a varied diet, a few grams of protein in a splash of milk on cereal makes little difference. It matters more if milk is a big part of your protein intake: for older adults trying to maintain muscle, for children, or if you’re vegan and relying on the drink as a protein source.
Calcium and Vitamin D: Fortification Does the Work
Cow’s milk naturally contains about 300 mg of calcium per cup, roughly 30% of the daily value on a US nutrition label. Plant milks contain little calcium of their own, so manufacturers add it. In the Minnesota analysis, 170 of the 233 products were fortified with calcium and vitamin D to levels similar to dairy milk. That’s good news, but it means unfortified or “organic” plant milks (which in some countries can’t be fortified) may provide very little.
Is added calcium absorbed as well?
Not always. In a 2000 study in the American Journal of Clinical Nutrition, Robert Heaney and colleagues at Creighton University tested calcium absorption in 16 men. Calcium from a fortified soy milk was absorbed at only about 75% of the efficiency of calcium from cow’s milk, and the authors concluded it was not a calcium source equivalent to cow’s milk at the same labelled amount. Other studies using different forms of added calcium have found absorption closer to cow’s milk, so the type of fortificant matters. You can’t usually tell which one a product uses from the front of the pack.
Shake the carton
Added calcium can also settle at the bottom. Heaney’s group reported in 2005 that much of the calcium in some fortified soy and rice drinks sank to the bottom of the container and wasn’t fully resuspended even by vigorous shaking by hand. Manufacturing has improved since, and most cartons now say “shake well” for this reason. It’s worth doing.
Iodine: The Nutrient People Forget
In countries like the UK, where salt isn’t routinely iodised, cow’s milk is one of the main sources of iodine. Iodine is needed for thyroid hormones and is especially important in pregnancy for the baby’s brain development.
A 2017 study by Sarah Bath and colleagues at the University of Surrey, published in the British Journal of Nutrition, measured iodine in 47 milk-alternative drinks (soy, almond, coconut, oat, rice, hazelnut and hemp). The 44 unfortified drinks had a median iodine concentration of about 1.7% of conventional cow’s milk. Only 3 of the 47 were fortified with iodine, even though many were fortified with calcium. The authors warned that people who switch to unfortified plant drinks could be at risk of iodine deficiency unless they get it elsewhere. They also advised against kelp supplements, which can provide too much iodine.
If you’ve switched to plant milk and you’re pregnant or planning a pregnancy, check whether your brand is fortified with iodine, or ask your doctor or midwife about other sources.
What Official Guidance Says
The Dietary Guidelines for Americans 2020–2025 count only fortified soy beverages as part of the dairy group, because their nutrient profile is similar to milk. Almond, oat, rice, coconut and other plant drinks are not counted. The guidelines note that they may still contain calcium, but their overall nutrition is too different. (We haven’t confirmed whether the 2025–2030 guidelines kept this exact wording.)
In February 2023 the US Food and Drug Administration published draft guidance on labelling plant-based milk alternatives. It allows names like “soy milk” or “oat milk”. It also recommends that products which are nutritionally different from milk carry a voluntary statement such as “contains lower amounts of vitamin D and calcium than milk.” It is voluntary and still a draft, so most labels won’t carry it. Read the nutrition panel instead.
Plant Milk for Children: Stricter Rules
This is where the choice matters most, because young children drink a lot of milk relative to their size and depend on it for protein, calcium and energy.
In 2019, a panel convened by Healthy Eating Research with the American Academy of Pediatrics, American Heart Association, Academy of Nutrition and Dietetics and American Academy of Pediatric Dentistry issued joint recommendations on drinks for children aged 0 to 5. They recommended plain cow’s milk and water from age 1, and advised avoiding plant-based milks such as almond, rice and oat drinks for young children unless there’s a medical reason, such as a cow’s milk allergy. The panel found little evidence that plant drinks offered any health benefit over cow’s milk at this age, and noted the risk of nutrient gaps if a child’s overall diet isn’t carefully planned.
UK government advice is broadly similar:
- Under 12 months: breast milk or first infant formula are the only suitable main drinks. Plant drinks and cow’s milk aren’t suitable as a main drink.
- From 12 months: unsweetened, calcium-fortified plant drinks such as soy, almond or oat can be part of a healthy, balanced diet.
- Rice drinks: the NHS says children under 5 shouldn’t have rice drinks because they may contain unsafe levels of arsenic.
If your child can’t have cow’s milk, speak to your doctor or a dietitian about the best substitute rather than choosing from the shelf.
Is Cow’s Milk Essential?
Not necessarily. In a 2020 review in the New England Journal of Medicine, Walter Willett and David Ludwig of Harvard argued that the evidence that high milk intake prevents fractures in adults is weak. They pointed out that countries with the highest dairy intake tend to have some of the highest hip fracture rates (which doesn’t prove milk causes fractures, but does suggest it doesn’t prevent them). They concluded that more than three servings a day isn’t justified, and that the right amount depends on the rest of your diet.
So adults who don’t drink cow’s milk, because of lactose intolerance, allergy, ethics or taste, can meet their needs from other foods. Choosing a plant milk just means paying attention to protein, calcium, vitamin D, iodine and vitamin B12 (which plant foods don’t naturally provide), rather than assuming the carton does it all.
Cow’s milk has its own issues. In some regions it can be watered down or adulterated. Our guide on how to identify adulterated milk covers simple checks.
Watch the Sugar in Flavoured Plant Milks
“Original” and flavoured versions of plant milks often contain added sugar, and barista or chocolate versions can contain a lot. Unlike the lactose naturally found in cow’s milk, these added sugars count towards the World Health Organization’s free-sugar limits. Our article on sugary drinks and type 2 diabetes explains why those limits matter. Choose “unsweetened” where you can.
How to Choose a Plant Milk
- Want the closest match to cow’s milk? Choose fortified, unsweetened soy milk. Pea-based drinks are another higher-protein option.
- Check the label for protein: around 7–8 g per cup is comparable to dairy. Many oat and almond drinks have 1–3 g.
- Check for calcium and vitamin D, and ideally iodine and B12 if you avoid dairy entirely.
- Pick unsweetened versions.
- Shake the carton before pouring.
- For children, follow the age guidance above, and never use rice drinks for under-5s.
Almond milk can still have a place in a varied diet. Our article on almond milk in winter covers ways to use it. Just don’t count on it for protein.
Frequently Asked Questions
Which plant milk is closest to cow’s milk?
Fortified, unsweetened soy milk. It has about 7 g of protein per cup, compared with about 8 g in cow’s milk, and it’s the only plant drink the US Dietary Guidelines count as part of the dairy group.
Is oat milk or almond milk healthier than cow’s milk?
Not nutritionally. Both are usually much lower in protein, and their calcium and vitamin D come from fortification. They can be part of a healthy adult diet if you get protein and other nutrients elsewhere, and unsweetened versions are low in sugar.
Can toddlers drink plant milk?
US health groups advise plain cow’s milk and water from age 1, and recommend avoiding most plant milks unless there’s a medical reason such as allergy. UK advice allows unsweetened, calcium-fortified plant drinks from 12 months as part of a balanced diet, but not rice drinks for under-5s. Ask your doctor or a dietitian if your child can’t have cow’s milk.
Do plant milks have as much calcium as cow’s milk?
Fortified ones often list similar amounts, but the added calcium can settle at the bottom of the carton, and some forms are absorbed less well. One study found calcium from fortified soy milk was absorbed at about 75% of the efficiency of cow’s milk. Shake the carton and check that the product is fortified.
